Manuel Valls, a former prime minister who resigned to run for the presidency but lost the Socialist primary race to left-winger Benoit Hamon, said he feared that support might be greater than anticipated for National Front leader Marine Le Pen and that he did not want to "take any risk with the republic."

Speaking on Wednesday, Valls said there was no way of removing Le Pen from the first round and that given the marginalization of Hamon, whose policies have proved divisive within his own ranks, he feared splitting too much of the vote.

Risk averse or canny?

Meanwhile, said Valls, the "moral collapse" of scandal-hit conservative Francois Fillon also made him a far-from-ideal candidate.

"I'm not going to take any risks," Valls told French broadcaster BFM TV, adding that, while he would vote for Macron, he would not be campaigning for him. "I have nothing to negotiate and am not asking for anything. I'm not joining his camp."

The endorsement could be seen as a mixed blessing for the 39-year-old Macron who, like Valls, served as a minister within the government of unpopular President Francois Hollande. Since announcing his campaign, Macron has sought to distance himself from the outgoing administration and paint himself as a bridge between left and right.

"I'm suspicious of the hidden agenda of politicians," Macron told a news conference on Tuesday, as a statement was anticipated from Valls about who he would support.

Onwards! and upwards

Macron has set his sights beyond the presidency to a June election for the French legislature, saying on Tuesday that his new party En Marche! (Onwards!) might be able to achieve a parliamentary majority.

Hamon - who signed a motion of no confidence against Valls' government last year - has faced dissent from fellow Socialists with a range of divisive left wing policies. They include the legalization of cannabis, taxes on robots and the introduction of a "universal income" for all citizens.

Valls is thought to be positioning himself to take over a battered Socialist party once the election is over, and to exert an influence within parliament.

However, the decision to back Macron was unpopular with Hamon supporters in the Socialist party. Arnaud Montebourg, a former minister under Valls and third in the socialist primary, was scathing of Valls' perceived party betrayal. "Now everyone knows what a commitment made by a man like Manuel Valls is worth: Nothing. Which is what a man without honor is worth," Montebourg tweeted.

rc/sms (AFP, dpa, Reuters)